Recently, several advances have been made in toothbrush design. Among these are what are usually called "angled toothbrushes" which are more convenient for brushing, most especially the back teeth, due to a bend or angle in the brush between the head portion and the handle portion.
Many designers have come up with what they consider to be the "perfect angle" for brushing, however as everyone is an individual, certain angled brushes are better than others depending upon the mouth and teeth of the user.
There are also known in the prior art several types of "resiliently deformable" toothbrushes. These resiliently deformable or flexible toothbrushes may have either a portion of the handle or neck which is resiliently deformable, as disclosed in U.S. Pat. Nos. 1,796,001 and 4,520,526 and International Patent Application No. WO88/06417, or may alternatively have a resilient head portion, as disclosed in several patents including U.S. Pat. No. 1,327,807, 2,445,651, 2,631,320 and 3,994,038.
The alleged advantage of these "resiliently deformable" or "flexible" toothbrushes is that in use, the resilient portion deforms in response to a force applied by the user, there ensuring that the pressure applied to the teeth and gums is the correct pressure to facilitate thorough cleaning without damaging the teeth or gums of the user.
The pressure applied to the teeth and gums by the user of these resilient deformable toothbrushes is, however, a function of the resilient characteristics of the toothbrush, these characteristics being dependent upon the material from which the toothbrush is constructed and the shape of the toothbrush.
Clearly, one such resilient toothbrush, for example, may assist a user to avoid applying exclusive pressure to his or her teeth and gums however, another user of the same toothbrush may not be applying the correct pressure to his or her gums even though it is the same pressure as that applied by the previous user, since a single resiliently deformable toothbrush does not take into consideration the individual characteristics of each user, each toothbrush being limited by its own resilient characteristics.
It can therefore be seen that in order for these resilient toothbrushes to in fact apply the correct pressure for each and every user, the resilient characteristics of each toothbrush must be tailored to suit the particular individual user.
Further, when these resilient type toothbrushes are removed from the mouth, they return to their original undeformed shape thereby giving no indication as to whether or not an excessive pressure was applied to the teeth and gums.
It will be clear to the person skilled in the art therefore that a user could use such a "resiliently deformable" toothbrush under the impression that it is applying the correct pressure to his or her teeth when, in fact, there is no indication whether or not that the particular "resiliently deformable" toothbrush suits that individual. Its use may have applied an excessive pressure to the teeth and gums of the user causing damage.
There are also known toothbrushes in which prior to use a user may select the desired oriententation between the head and the handle, such a toothbrush is described in U.S. Pat. No. 4,829,621. U.S. Pat. No. 4,712,266 discloses a dental whisk in which the head and handle rejoined by a region of reduced cross-sectional area to allow the angle between the head of the whisk. In each of these patents it is the intention of the designer that once the angle between the head and the handle of the brush or whisk is selected it will remain as selected during use even if the user applies excessive brushing pressure. There is no teaching in either patent of the desirability of the angle between the head and the handle of the brush or whisk changing due to the application of excessive brushing pressure.
Clearly there is also a need for a toothbrush the shape of which can be individually matched to the user's mouth, by the user and which will positively indicate to the user that he or she has been applying excessive brushing pressure to his or her teeth.